Making a timing strut

To go sprinting, you will need a timing strut fixed to the front of the car to break the timing beam that its part of the timing equipment used to measure your time. They are fairly easy to make and the dimensions are quoted in the MSA motor sport handbook that comes with the MSA competition licence. The main problem is actually working out how to attach them to the car rather than making the strut itself. Remember, they have to be removed after the sprint! The one that I have used is circled in the picture above.

Strut material

They are usually made of aluminium which is strong and light. It also has the advantage of being easily bent which means that the strut can often be made as a single unit. It should have a matt black fnish and be vertical when fitted to the car.

The strut itself

Rounding the corners is a good idea so that there are no sharp edges. The main strut should be about 10-12 inches long with the bottom of the strut just a few inches off the ground. The MSA Blue book will define the exact dimensions. The dimensions in the diagram are approximate so very often scrap metal can be used. The front edge of the strut should be clear of the car so that it is the first thing to break the beam. In practice, most struts have the vertical section completely clear so that there is no argument over whether it is clear of the bodywork or not.

Using the number plate

This method uses one of the front number plate screws to attach the strut to the car. The shape of the strut is L-shaped with an inch or so of the horizontal length bent at 90 degrees to form a right angle. A suitable hole can be drilled through this for the screw to go through.

Using the number plate screw

Using a split bracket and tape

A variation on this is to cut the aluminium and bend half the bracket to the right and half to the left. Carpet tape can then be used to tape the bracket onto the number plate.

Using the radiator grill

This method uses the same method but bolts the strut through the radiator grill.

Using the front bumper

Mine was made from an single A4 sheet of 2-3 mm thick aluminium sheeting which was painted black and then covered in black carpet tape to give it a softer feel.

Making a bumper strut

Parts of it are padded with foam where it fits over the front bumper to protect the bodywork from damage. This is extremely good for wedges and is the method that I use.

Fixing a bumper strut (looking down)

This strut was made in two pieces. The L shape is made with a shorter horizontal length. The bracket is made from a T piece and can be cut from an A4 sheet of metal if needed. The T piece is folded three times. Two horizontal folds are made to push the top and bottom sections back to match the profile of the bumper. The third fold is made vertiacally to create a right angle bracket for the actual timing strut. You may need to adjust the angles to get a good fit. Put a tea towel over the bumper to protect it while you do this. The inside of the bracket should be covered in foam to protect the bodywork. I then covered mine with strips of black carpet tape (aka gaffa, tank, duct tape ) so that there are no sharp edges to damage anything. It is then taped to the bumper to position the strut. The strut must be vertical so drill one hole to act as a pivot to position the strut correctly before drilling the rest of the holes and rivetting the two units together. The strut is rivetted or glued in place and covered with some more tape. To fix it, push it over the bumper and fix in place with a couple of pieces of carpet tape.

Summary

It takes about 30 minutes to make and I'm sure there are many other ways of fixing the strut, but these methods are the most commonly used.